In a race that remains very much a toss-up mere hours before election day, both sides can agree that a very small margin of voters will decide whether Colorado goes red or blue tomorrow. It is for that reason that some Republican Party officials in the state say they're particularly worried about reports that voters trying to cast ballots for Mitt Romney are seeing Barack Obama show up on the screen.

As we reported on Friday, the Republican National Committee sent a letter to six states, including Colorado, expressing concerns about reports that votes intended for Mitt Romney were going to Barack Obama. In Colorado, the letter was triggered by an article in the Grand Junction Daily Sentinel, which reported that one voter, who ended up successfully voting with a paper ballot, complained that the machine was not choosing the candidate he wanted.

Supporters at Mitt Romney's final Colorado rally on Saturday.

Photo by Brandon Marshall

The Clerk and Recorder for Mesa County told us there was no reason to be concerned, noting that her office re-calibrated the machine in question before taking it out of commission out of an abundance of caution.

Since then, concerns from the Pueblo County Republican Party have emerged, with GOP officials filing a formal complaint after they say they received more than a dozen calls or letters of concern about the machines not working properly and generally favoring Obama over Romney.

"Pueblo is a critical swing county for Colorado," says Pueblo GOP Chairwoman Becky Mizel. "So we are concerned."

In Pueblo, according to the latest turnout data from the Secretary of State's office, 24,514 Democrats, 13,371 Republicans and 10,294 unaffiliated voters have cast ballots during the early vote period.

Mizel says the local party has heard fifteen complaints, with individuals worried their vote for Romney was going to the president. Since this went public, she adds, more people have been coming forward, saying they are worried about possible glitches that could have impacted their vote for the Republican candidate.

"When we first heard about it, it sounded bizarre that a...Romney vote would...go for Obama," she says, "And we kept hearing about it over and over again."

To some, the problem, as we explained in our story on the Mesa County situation, is that it's possible for the screen not to be properly calibrated to touch. In that scenario, an attempt to press a candidate on one place could be recorded incorrectly by the machine.

Officials, however, aren't concerned with this problem. They say the machines have been tested and that it's usually just some form of human error, i.e. touching the wrong place on the screen. Further, there are several steps along the way during which a voter directly verifies that the choice has been recorded properly. For that reason, it would be very obvious if the machine was not recording the candidate the voter wanted.

"It's not so much the people who caught it -- it's the ones who didn't catch it that we're worried about," she said, "The elderly, who don't necessarily know to double check.... It can still get by you."

She added, "Our problem went all through early voting [which ended on Friday]."

Continue for the response from the Secretary of State's office and the Pueblo County Clerk and Recorder.

The office of Secretary of State Scott Gessler, a Republican, says it has deployed staff to review the operability of the machines in Pueblo and should have more information later today. A spokesman for Gessler says the office has received a handful of complaints now being investigated by staffers. In addition to the inquiries last week regarding Mesa County, and now the Pueblo concerns, they have also been looking into Adams County.

Gilbert Ortiz, the clerk and recorder for Pueblo County, says there is no reason to be concerned. However, he does wonder what effect the reports could have on election day.

Supporters at Barack Obama's rally last night.

Photo by Brandon Marshall

"We have one person that has, by writing, alleged that there was a voting machine error," says Ortiz, who is a Democrat. "They made the accusation that it was auto-filling Obama's name no matter where they touched on the screen...but they were able to vote for Mitt Romney."

Ortiz says that the county has received nine complaints total. In each case, though, staffers on site were able to determine that "it wasn't a machine error."

Like officials in Mesa County, Ortiz also points out that there are three different opportunities to verify the vote and many protections in place with these machines, which his county has been using since 2006.

He adds, "What we think this is, is a user error. When you're texting somebody, it's very easy to hit the wrong button, and we believe that's what people were doing...simply hitting the wrong button."

In the past, he says, these machines have come under scrutiny from both parties, but he says he has never seen this level of concern.

"We've had complaints in the past...and we have [election] judges walk up to the machines and make sure they weren't malfunctioning," he says. "But this time, the party called the press; there's a letter from the RNC."

He says such questions have not usually been this contentious, which makes him speculate about a possible push for a recount or challenge.

(This could be particularly problematic given how close the vote in Colorado is likely to be and how important its nine electoral votes are to the candidates. And in swing states like Ohio and Florida, there are already major controversies around early voting).

"We're expecting push-back, no doubt, but [in] Pueblo County, because we are following all the rules...we feel assured that our machines would be vindicated," he says, adding, "I wish I knew what to expect, so that I could prepare...but I have no idea."

Mizel, as a county chair, said she wouldn't have the authority to push for any kind of recount and would only support one if the Secretary of State's office and other officials discovered serious problems.